alkali

/al·ka·li/ (al´kah-li) any of a class of compounds with pH greater than 7.0, which form soluble soaps with fatty acids, turn red litmus blue, and form soluble carbonates, e.g., hydroxides or carbonates of sodium or potassium.

alkali

[al′kəlī]

Etymology: Ar, al + galiy, wood ash

a compound with the chemical characteristics of a base. Usually used with reference to hydroxides of Group I metals and ammonium, alkalis combine with fatty acids to form soaps, turn red litmus blue, and enter into reactions with carbon dioxide that form water-soluble carbonates. See also acid, base. -alkaline, adj., alkalinity, n., alkalinize, alkalize,v.

alkali (al´kəlī),

alkali

any one of a class of compounds such as sodium hydroxide that form salts with acids and soaps with fats; a base, or substance capable of neutralizing acids. Other properties include a bitter taste and the ability to turn litmus paper from red to blue. Alkalis play a vital role in maintaining the normal functioning of the body chemistry. See also acid-base balance, alkaline, base.

the ability of the combined buffer systems of the blood to neutralize acid. The pH of the blood normally is slightly on the alkaline side, between 7.35 and 7.45. Since the principal buffer in the blood is bicarbonate, the alkali reserve is essentially represented by the plasma bicarbonate concentration. However, hemoglobin, phosphates and other bases also act as buffers. A lowered alkali reserve means a state of acidosis; increased reserve indicates alkalosis. Alkali reserve is measured by the combining power of carbon dioxide, which is the amount of carbon dioxide that can be bound as bicarbonate by the blood.

Precipitation over a greater temperature range in the alkali basalts yields more variation in the Fo contents (BVSP, 1981, p.

Le Bas (1962) showed that lower magmatic Si contents in alkali basalts, when compared to tholeiites, can cause more Al to substitute for Si in augite tetrahedral sites.

Higher alkali-metal concentrations in alkali basalts result in plagiodases having higher [K.

As the plate moves over the plume tall, melting percentages and magma production drop as alkali basalts and their differentiates appear during the post-shield stage.

Classic experiments by Yoder and Tilley in the 1960's showed that Ne-normative alkali basalts are probably not related to tholeiitic basalts by differentiation because of a low-pressure thermal divide approximately coinciding with the Ol--Ab join in the basalt tetrahedron (Fig.

230]Th, differentiation of alkali basalt to form trachyte in deep magma chambers (e.

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